Aims and objectives
Acute pulmonary embolism (PE) is a common pulmonary disease which could lead to health problems if not diagnosed in time.
The current reference standard the radiologist uses to diagnose PE is a Computer Tomography Pulmonary Angiogram (CTPA)1.
The sensitivity of the CTPA is estimated 83%-100% and its specificity between 89%-98%2-4.
Adequate use of Computer-Aided Detection (CAD) techniques may be a resource to support the radiologist in the detection of PE5-7.
Scan quality is proven to be of influence on the software performance.
Methods and materials
We included CTPAs from two months scanned on a 256-slice CT-scanner with available raw data and a minimum of 200 Hounsfield Units (HU) in the main pulmonary trunk.
Primary diagnosis was made by the on-call radiologist and for this research the scans were re-evaluated by a thorax-radiologist.
Differences were resolved in a consensus meeting with a third thorax-radiologist and the final diagnosis used as reference standard.
All scans were reconstructed with both HIR (level 4 out of 6 levels) and MBIR (level 1 out of...
We included the available 100 CTPA-patient scans (51% female,
average age 62,3 years).
According to the reference standard 17% was positive for pulmonary embolism.
Interobserver agreement for the reference standard was K=0,97.
Interobserver agreement for evaluating the CAD-detections on a per-CAD base on HIR (n=416) and MBIR (n=475) was respectively K=0,66 and K=0,59.
A 100% sensitivity was perceived in both reconstruction methods.
HIR reconstruction shows a higher outcome with respect to the MBIR reconstruction concerning specificity and PPV.
A significant difference was not evinced.
We found a significant increase in image quality,
defined as SNR and CNR,
with use of MBIR over HIR.
Never the less this did not improve the specificity and PPV.
The sensitivity en NPV did not differ and stayed maximal,
making the software in daily practice very useful to exclude PE if no CAD-detections are found and this could improve radiological workflow.
Department of Radiology
Dokter van Heesweg 2
8025 AB Zwolle,
CTPA as the gold standard for the diagnosis of pulmonary embolism.
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